Patent GB-1053140-A (GB)
IPC: B24B49/18
Abstract: 1,053,140. Trueing grinding wheels. NEWALL ENGINEERING CO. Ltd. Dec. 15, 1965 [Dec. 16, 1964], No. 51273/64. Heading B3D. Grinding apparatus comprises a grinding wheel 15, a dressing tool 30 operable to dress the grinding wheel, and automatic control means for controlling operation of the dressing tool as a function of three quantities viz. the time in the grinding life of the grinding wheel, the radial feed transmitted to the dressing tool at each dressing operation, and the time interval between successive dressing operations, not more than one of the last two mentioned quanties being maintained constant. The grinding wheel is mounted on a carrier 14 having guide-ribs 13 engaging guideways on a base 10, the carrier being movable by means of a feed screw 17 engaging a follower 14a on the carrier towards and away from a workpiece carrier 12 movable along guideways 11 on the base. The feed screw 17 is, at one end, connected to a piston 19a movable in a cylinder 19b for effecting rapid movement of the grinding wheel, and, at its other end, is keyed to a shaft 18 connected by gearing 20, 21 to a gear 23 engageable by a plunger 24 of a hand wheel 25. Feed movements are imparted to the grinding wheel by the hand wheel 25 or automatic means connected to the shaft 18. The dressing tool 30, which is diamond tipped, is carried by a sleeve 31 movable in a slide 32 by a cam screw 36 engaging a follower 37 in the sleeve. The slide 32 is movable along guides 34 on a plate 33 secured to the carrier 14 by an hydraulic motor 35. The cam screw has a ratchet 39 engaged by a pawl 40 operated by a control device 41 actuated by a counting mechanism 42 having an arm 43 which is operated by finished articles 44. The mechanism 42 is set to operate the device 41 after a predetermined number of articles has been counted so that the dressing tool is advanced and the motor 35 actuated at substantially constant intervals in the life of the grinding wheel. The cam screw 36 has a varying pitch so that as the diameter of the wheel decreases, the depth of each dressing operation is increased. To compensate for the increase in depth of each succeeding dressing operation, the lead screw 17 also has a varying pitch so that for each feeding movement forward to compensate for wear and the dressing operation, the carrier 14 moves an increasing amount as the diameter of the grinding wheel decreases. In another embodiment, the cam screw 36 and feed screw 17 are replaced by screws having a constant pitch, and the device 41 for actuating the ratchet on the screw is actuated by a counting mechanism 50 having a lever 51 operated by the finished articles 52, Fig. 3 (not shown). The counting mechanism 50 is connected to a photo-electric device 53 which embraces the grinding wheel 15 and operates the counting mechanism in such a way that as the diameter of the wheel decreases, the number of articles 52 required to instigate a dressing operation is progressively reduced. In a further embodiment having cam and lead screws of constant pitch, the screws are rotated through angles which progressively increase at each dressing operation as the diameter of the wheel decreases by a pulse-operated motor connected to the screws under the control of a photo-electric device similar to the device 53. In another embodiment the sleeve is advanced by a motor-driven cam.